Resistance conductor and manufacturing process and material therefor



Au M, 1925. 1,549,394

W. S. TYLER RESISTANCE CONDUCTOR AND MANUFACTURING PROCESS AND MATERIALTHEREFOR Filed Jan. 20, 1923 10 6 2 r 5 1 I 9 g ;g:3 i 2 2 9 2 INI 'ENTOR. H/al 4321a? Zyler I TREY Patented Aug. 11, 1925.

UNITED "STATES PATENT 4 OFFICE WALTERS. TYLER, ornnrnsnroar,c'onnncirou'r, 'assrenon, BY MESNE ASSIGN- mnnrs, 'ro commnm rnonoenarnCOMPANY, 11m, A conrorm'rron or new YORK. I

RESISTANCE CONDUCTOR AND MANUFACTURIN' G PROCESS AN D MATERIAL THEREFOR.

Application filed January 20, 1923. Serial No. 613,860.

- To all whom it may concern:

Be it known that I, WALTER S. TYLER, a citizen of the United States, anda resident of the city of Bridgeport, county of Fairfield, and State ofConnecticut, have invented certain new and useful Improvements inResistance Conductors and Manufacturing Processes and Materials Thereforof which the following, taken in connection with the accompanyingdrawings, is a specification.

This invention relates to resistance elemerits-i. e. conductors of highresistivitycapable of being calibrated to any desired resistance value,and to the method or process of producing the same.

An object of the-invention is to provide a relatively high resistanceunit having relatively small dimensions, and with practically noinductance or capacity, this unit being especially applicable for use inradio-receivingsets. v

Another object is to provide a resistance which can be readilycalibrated to a prede--' termined resistance value and without'alteringits composition; and which, moreover, is not materially aifected bysmall or ordinary temperature changes, and yet is capable of permanentchange through material variations in temperature. A further object isto provide a resistance conductor whose resistance value may be raisedby reducing its cubical contents, and

yet lowered,

bfy polishing or rubbing its surface. Also, i t

he resistance becomes too low by this polishing or rubbing, it may beinunit structure adapted to have both -a plurahty of essentiallypredetermined resistance values, and also an value.

Then, an object-is to provide aresistance unit having a condensereffect.

Finally, an object is to provide a non inductive resistance havinglittle or no condenser effect.

lVith these and other objects in view,as

will hereinafter more fully appear, the invention is described in thefollowing specification, taken in connection with the accom-' panyingdrawings, in which- Fig. -1 is a-perspective view of a composite form ofthe invention, including all of'the novel features thereof, butdisclosing; of

easily variable resistance course, only the structure of the invention,

the composition and process of manufacture being hereinafter broughtout;

Fig. 2 is a magnified, cross-sectional-view thereof, taken on the line2+2 of F igf I;

In'the drawings, for illustrative purposes only, the article is shown asrectangular in outline and consisting of a slab of the greaterresistance material 1-, having a greater conducting coating 2, thiscoating being formed by rubbing or polishing in manner as hereafterexplained. The slab is a composite structure arranged to have thevarious characteristics heretofore suggested.

One part of the unit, marked B, has three I binding-post terminals, 3, 4and 5, one of whichas, for instance, 5is movable longitudinally towardand away from the others by being mounted in a longitudinal slot formedin the unit. This'is accomplished 'by unscrewing both the lock nut 6,Fig. 2, and

a the binding nut 7 ,on the stud screw 8, thereby releasing theconducting washers 99 from gripping contact with the surface .of'

the unlt, and permitting this entire bindingpost assembly to be moved inits slot, and

-soalter the distance between the two terminals 5 and 4, or 5 and 3.Moving the terminals together reduces the resistance, and vice versa.This structure constitutes not only a novel means of calibrating theunit to any it from the unit itself. Thus there is to posts 3, 4, and 5,except that the stud screw 14, is slightly longer to accommodate aninsulated .washer 15, as shown in Fig. 2; thiswasher, in the embodimentshown, having also a hollow tubular portion 16 adapted to house thestudscrew 14, and to insulate provided a binding- 20 tact is made witthe resistance unit on one surface only. By' inserting the bindingpostsin part A of'the unit in reverse position, as shown at 12 and'13, Fig.1, contact is made between the top surface at 12, and the bottomsurface, at'13. Thus a condenser is provided in combination with theresistance unit, its effect being controlled, for instance, by thedistance between the conducting plates 11-11, and the distance between:3 .the terminals 12 and 13. This composite structure, with itsplurality of. binding-posts, provides a convenient means of getting avariety of resistance and condenser effects, simply by connecting tovarious pairs of binding posts.

I 1 Various substances can be used for the non-conducting .and theconducting elements of the compound. As the conducting element, it ispreferred to use graphite. For

40 the non-conducting element, various substances or theircombinationscan be used, preferably a plastic compositionincluding chinaclay Congo gum, and shellac, in proportlons bout the same as that usedin the 4 manufacture of phonograph records-as, for instance, more orless, of chinarlay; 5%, more or less, of Congo gum; and 25%,

' more or less, of shellac.

- These ingredients are mixed in a finely 50 divided state, eithergranulated, .but preferably in powdered form, the finer the ingredientsthe better, as it obviates any slight ares which might form 'betweenthe'gralns of granulated material. 7

To this non-conducting composition is added graphite or other conductingmaterial In a PIOPOI'UOH such that the approximate final resistancevalue of the unit will be approximately as desired. All of theingredients, having been brought to a very fine state, are thoroughlymixed, preferably in the presence of heat and allthe particles of thecon 7 are divided or separated non-conducting material.

ressnrc, so that ucting material l iyilparticles of.

e more intist structure in which conresistance.

mate the mixture, the better the result. The heat, when used, serves tomelt the gums in the non-conducting composition; and to aid in morethoroughly mixiugthe various ingredients.

After the material is thus mixed, it is heated on a steam table, andformed into suitable blocks, or other units, under a set of moldingdies. It is then removed and allowed to harden. The terminals may beembedded within the composition at the time of ressing, or insertedafterwards.

Applicant has discovered that, in addition to theknown ways ofcalibrating each unit to any desired resistance-such, for instance, asaltering its length between terminals, or the resistance value of thematerial itself-- 'the same result may be secured by removing theexterior surface of the resistance member by abrasion in such mannerthat no polishin eflect takes place. Also, and in place of th1s,'by theuseof a solvent, such as alcohol, for dissolving away the conductinggraphite coating. By thus removing the coatin or the member, theconductivity 0 the skin 0 body, as a whole, is largely reduced, or,which is the same thing, the resistance increased. a I

Another means of calibratingthe resistance unit for an increase inresistance, is to allow current to pass through it sufiicientlystrong toeffect a heating action or to otherwise heat the unit. The shellac in Ithe composition will be melted and caused to flow more completely aroundthe different particles of graphite, and so eflect this increasedresistance.

Another means to alter the resistance value, is to actually removesuflicient of the material between terminals to appreciably alter thecross-sectional area of the unit; this also results in increasing the Inthe event the unit has-thus had its resistance increased beyond thedesired, amount, a reverse calibration effect can be produced bypolishing, so as to bring the aphite particles on the surface into moreintimate contact.

Obviously, various kinds of ingredients, suitable for the purposestated, will suggest themselves to those skilled-in the art. Likewise,the proportions of these ingredients can be varied within quite widelimits, d e pending upon the characteristics of the spe cificingredients used, and the distance between terminals of the resistance,and the amount of resistance desired.

Therefore, itis understood that the scope of the invention is not to beconsidered as limited to the particular materials, structure, and methoddescribed, but instead, solely by that covered in the appended claims.

Having thus described the nature of this invent-ion anda preferred formand method for same, what is claimed and for which Letters Patent of theUnited States is desired, is

1. The method of manufacturing resistances, which consist in mixing aclay, a gum and a shellac with graphite, to form a thermoplasticmaterial, in molding the composition to the desired form under theapplication of heat and pressure and in allowing it to cool and harden.

2. A resistance member containing a clay, a gum, shellac and graphite.

3. A resistance member consisting of a clay, a gum, a shellac, and asuitable conducting material intermixed therewith.

4. A variable resistance including a body portion of predeterminedresistance, a pair of binding posts secured to said body, sheets ofinsulation material spaced from the binding posts and contacting withthe body, sheets of conductor material disposed on the insulation, and asecond pair of bolts passing through the laminated portion of the unit,and each contacting with one of the sheets of the conductor material.

5. A resistance unit containing china clay, Congo gum and shellac, mixedin approximately the following proportions, china clay 70%, Congo gum 5%and shellac 25%, together with graphite.

Signed at Bridgeport, in the county of Fairfield and State ofConnecticut, this 18th day of January, A. D. 1923.

WALTER S. TYLER.

